Moai (besides the big statues on Easter Island) is an Open Source game engine for developing (mostly) 2D games for Windows, Mac, Linux, iOS, Android and Chrome (NaCl?).
It garnered some attention because it is now used in some high profile Kickstarter projects, the Double Fine Adventure (Codename: Reds), and Shadowrun Returns. These projects have also started to feed some of their engine development upstream, bringing the experience of AAA game developers back into the codebase.
It is designed so that usually the game developer only uses Lua to write the game. All base needs are fulfilled by the engine and exposed to this scripting language (which is very popular among game developers due to the simplicity and efficiency).
In case you're wondering why there's pricing all over the Moai page: The company finances itself by selling a cloud hosting service. The engine SDK itself is open source and gratis.
So, What's the Connection to Metalab?
We're planning to hold workshops for the engine at Metalab. Jay Vaughan has deep experience with the engine, having developed multiple commercial projects with it, and he'd like to share his knowledge with everybody at Metalab who is inclined to listen, with the prospect of holding code jams afterwards.
I have some experience with holding workshops here, and I'm very interested in learning the engine myself, that's why I'm helping with the organization of the event.
The first workshop is planned to happen on Friday, September 14, 2012. It's free and open for everyone to attend!
Jay plans to dive into the technology very quickly. If you plan to attend, please install Moai to a state where it compiles! We will go straight into programming Lua, so the moai binary should be readily available.